Wideband RFI Cancellation Using true-time delays and a Hadamard Projection Operator

Radio frequency interference (RFI) in a devastating problem for high-sensitivity phased arrays. This paper explores a method of mitigating RFI in a receiving array using a combination of true-time delay with a truncated Hadamard projection that can place a wide-band spatial null over the RFI. The operations involved can be performed with analog circuity before sampling for the digital signal processing engine in order to enhance dynamic range. The modified beamformer solution is briefly derived and performance is compared to the existing maximum SINR beamformer using analytical phasor domain models. The results show successful null placement at the expense of control of the main lobe shape and side lobe levels.